When to Plant Cauliflower in Clayton County, IA
Cauliflower is a cool-season brassica that produces dense white, purple, or green heads called curds. It is more finicky than broccoli but rewards with a mild, nutty flavor.
Clayton County, Iowa is in USDA Zone 4b. The average last spring frost is April 30 and the first fall frost is October 7, giving you a growing season of approximately 160 days.
At an elevation of 1,343 feet, Clayton County receives approximately 32.8 inches of rainfall annually with predominantly silt loam soil. Summer highs average 81°F, so choose short-season varieties of Cauliflower to ensure they mature before fall.
Clayton County Soil Profile
Soil Type
Silt Loam
Soil pH
5.9-7.3
Drainage
Well Drained
Plant Planting Risk Windows
Percentages indicate frost risk at transplant. The 70% safe window means there is a 30% chance of frost after transplant — suitable for cold-hardy crops or gardeners with frost protection. The 90% safe window is best for tender plants.
Plant Water Budget
Cauliflower Planting Timeline — Clayton County, IA
Cauliflower Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | March 19 | Mar 19 – Apr 2 |
| Transplant Outdoors | April 30 | Apr 30 – May 14 |
| Direct Sow | April 23 | Apr 23 – May 14 |
| Fall Sowing | July 15 | Jul 15 – Jul 29 |
| Harvest | June 25 | Jun 25 – Aug 27 |
Plant 1" deep · 15" apart · Rows 24" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | Start Indoors |
| April | Start Indoors Transplant Outdoors Direct Sow |
| May | Transplant Outdoors Direct Sow |
| June | Harvest |
| July | Fall Sowing Harvest |
| August | Harvest |
| September | — |
| October | — |
| November | — |
| December | — |
Growing Conditions
Sun
Full Sun (6-8+ hours)
Water
High — keep soil consistently moist
Days to Maturity
55–100 days
Soil pH
6 – 7
USDA Zone
Zone 4b
Growing Season
160 days
Growing Tips for Clayton County
Start seeds indoors 6 weeks before transplanting. Blanch white varieties by tying outer leaves over the head. Provide consistent moisture and avoid temperature extremes.
Companion Planting
Good Companions
Avoid Planting Near
Level Up Your Garden
Cauliflower in Other Locations
Frequently Asked Questions
When should I plant Cauliflower in Clayton County, IA?
Clayton County is in Zone 4b with an average last frost of April 30. Plan your Cauliflower planting based on this frost date — see the calendar above for exact timing.
What planting zone is Clayton County, IA?
Clayton County, Iowa is in USDA Hardiness Zone 4b. The average last spring frost is April 30 and first fall frost is October 7.
Plan Your Garden with Confidence
Get our free Garden Planner — designed to help Clayton County gardeners in Zone 4b organize planting dates, track what's growing, and never miss a planting window.
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